Jefferson Gomes de Souza1, Juan Del Coso2, Fabiano de Souza Fonseca3, Bruno Victor Corrêa Silva4,5, Diego Brito de Souza6, Rodrigo Luiz da Silva Gianoni7, Aleksandra Filip-Stachnik8, Julio Cerca Serrão9, João Gustavo Claudino4,7,9,10. 1. Laboratory of Nutrition and Sports Training, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil. 2. Centre for Sport Studies, Rey Juan Carlos University, Fuenlabrada, Spain. 3. Physical Education Department - Laboratory of Sports Science, Federal Rural University of Pernambuco, Recife, Pernambuco, Brazil. 4. Faculty of Physical Education, University of Itaúna, Itaúna, Minas Gerais, Brazil. 5. Physical Education College, University Center of Belo Horizonte -Uni BH, Belo Horizonte, Minas Gerais, Brazil. 6. Exercise Physiology Laboratory, Camilo José Cela University, Madrid, Spain. 7. Research and Development Department, LOAD CONTROL, Contagem, Minas Gerais, Brazil. 8. Institute of Sport Sciences, The Jerzy Kukuczka Academy of Physical Education in Katowice, Katowice, Poland. a.filip@awf.katowice.pl. 9. Laboratory of Biomechanics - School of Physical Education and Sport, Universidade de São Paulo, São Paulo, São Paulo, Brazil. 10. Department of Physical Education - Center for Health Sciences, Federal University of Piauí, Teresina, Piauí, Brazil.
Abstract
PURPOSE: The aim of this study was to systematically review evidence on the prevalence and magnitude of side effects associated with caffeine supplementation in athletes. METHODS: Systematic searches through the PubMed, VHL, Scopus, and Web of Science databases were conducted according to the PRISMA guidelines. Peer-reviewed articles written in English that reported the prevalence/percentage or magnitude/effect size of side effects after caffeine supplementation in athletes in a sports context were included. Studies were grouped by the dose of caffeine administered as follows: low = ≤ 3.0 mg/kg; moderate = from 3.1 to 6.0 mg/kg; high = ≥ 6.1 mg/kg. The magnitude of the side effects was calculated with effect sizes. RESULTS: The search retrieved 25 studies that met the inclusion/exclusion criteria with a pooled sample of 421 participants. The supplementation with caffeine produced a higher prevalence or magnitude of all side effects under investigation when compared to placebo/control situations. The prevalence (magnitude) was between 6 and 34% (ES between 0.13 and 1.11) for low doses of caffeine, between 0 and 34% (ES between -0.13 and 1.20) for moderate doses of caffeine, and between 8 and 83% (ES between 0.04 and 1.52) with high doses of caffeine. The presence of tachycardia/heart palpitations and the negative effects on sleep onset had the highest prevalence and magnitude, in athletes using supplementation with caffeine. CONCLUSION: In summary, caffeine supplementation in the doses habitually used to enhance physical performance produces several side effects, both after exercise and at least 24 h after the ingestion. However, the prevalence and magnitude of side effects with high doses of caffeine were habitually higher than with low doses of caffeine. From a practical perspective, using ~3.0 mg/kg of caffeine may be the dose of choice to obtain the ergogenic benefits of caffeine with the lowest prevalence and magnitude of side effects.
PURPOSE: The aim of this study was to systematically review evidence on the prevalence and magnitude of side effects associated with caffeine supplementation in athletes. METHODS: Systematic searches through the PubMed, VHL, Scopus, and Web of Science databases were conducted according to the PRISMA guidelines. Peer-reviewed articles written in English that reported the prevalence/percentage or magnitude/effect size of side effects after caffeine supplementation in athletes in a sports context were included. Studies were grouped by the dose of caffeine administered as follows: low = ≤ 3.0 mg/kg; moderate = from 3.1 to 6.0 mg/kg; high = ≥ 6.1 mg/kg. The magnitude of the side effects was calculated with effect sizes. RESULTS: The search retrieved 25 studies that met the inclusion/exclusion criteria with a pooled sample of 421 participants. The supplementation with caffeine produced a higher prevalence or magnitude of all side effects under investigation when compared to placebo/control situations. The prevalence (magnitude) was between 6 and 34% (ES between 0.13 and 1.11) for low doses of caffeine, between 0 and 34% (ES between -0.13 and 1.20) for moderate doses of caffeine, and between 8 and 83% (ES between 0.04 and 1.52) with high doses of caffeine. The presence of tachycardia/heart palpitations and the negative effects on sleep onset had the highest prevalence and magnitude, in athletes using supplementation with caffeine. CONCLUSION: In summary, caffeine supplementation in the doses habitually used to enhance physical performance produces several side effects, both after exercise and at least 24 h after the ingestion. However, the prevalence and magnitude of side effects with high doses of caffeine were habitually higher than with low doses of caffeine. From a practical perspective, using ~3.0 mg/kg of caffeine may be the dose of choice to obtain the ergogenic benefits of caffeine with the lowest prevalence and magnitude of side effects.
Authors: Kristina L Kendall; Jordan R Moon; Ciaran M Fairman; Brandon D Spradley; Chih-Yin Tai; Paul H Falcone; Laura R Carson; Matt M Mosman; Jordan M Joy; Michael P Kim; Eric R Serrano; Enrico N Esposito Journal: Nutr Res Date: 2014-04-13 Impact factor: 3.315